Camshaft device of a motor vehicle internal combustion engine

ABSTRACT

In a camshaft adjusting device of a motor vehicle internal combustion engine which has an electromagnetic braking unit that includes a stationary actuator having a first braking surface and an axially spaced second braking surface which is movable relative to the first braking surface, the braking unit further includes a brake disk which is functionally separate from the stationary actuator and is at least partially situated between the spaced braking surfaces of the actuator and connected to an adjusting input of the camshaft adjusting device.

This is a Continuation-In-Part application of pending international patent application PCT/EP2012/003697 filed 2012 Sep. 4 and claiming priority of German patent application 10 2011 116 1647 filed 2011 Oct. 14.

BACKGROUND OF THE INVENTION

The invention relates to a camshaft adjusting device of a motor vehicle internal combustion engine with an electromagnetic braking device for controlling the phase position of the camshaft.

An electromagnetic camshaft adjusting device of a motor vehicle internal combustion engine having a mechanical braking unit is already known from DE 10 2008 050 824 A1. It includes a brake disk which is part of the electromagnetic actuator of the braking unit.

A mechanical camshaft adjusting device is known for example from U.S. Pat. No. 6,457,446 B1, in which the function of the actuator is independent of the brake disk.

The object of the invention in particular is to provide a cost-effective camshaft adjusting device which has short adjustment times.

SUMMARY OF THE INVENTION

In a camshaft adjusting device of a motor vehicle internal combustion engine which has an electromagnetically actuated braking unit that includes a stationary actuator having a first braking surface and an axially spaced second braking surface which is movable relative to the first braking surface, the braking unit further includes a brake disk which is functionally separate from the stationary actuator and is at least partially situated between the spaced braking surfaces of the stationary actuator and connected to an adjusting input of the camshaft adjusting device.

The actuator and the brake disk may be optimized independently of one another, so that the adjustment time needed for the setting of the phase position of the camshaft of the motor vehicle internal combustion engine is reduced. The necessary installation space, weight, and/or energy consumption of the camshaft adjusting device is also reduced, and costs are lowered. The mass inertia is decreased by reducing the mass of the brake disk, as a result of which the adjustment speed is increased. A cost-effective camshaft adjusting device having short adjustment times may thus be provided. A “stationary actuator” is understood in particular to mean an actuator having a stationary housing. The term “stationary” is understood in particular to mean fixed in place, i.e., permanently installed, preferably with respect to a housing of the motor vehicle internal combustion engine. The stationary actuator preferably has no rotating components. A “braking surface” is understood in particular to mean a surface of the actuator that is provided for establishing a connection to the brake disk with frictional engagement in order to supply a braking torque. An “actuator” is understood in particular to mean a component that has at least one movable actuating element which is preferably situated so as to be displaceable relative to the housing of the actuator. The actuator is preferably provided for converting an electronic and/or electrical signal into a mechanical movement of the actuating element. The actuating element is advantageously provided for actuating the brake disk. The actuating element is preferably directly in contact with the brake disk for the actuation. “A brake disk and an actuator which are functionally separate from one another” is understood in particular to mean that the actuating element of the actuator and the brake disk are separate from one another, as the result of which the actuator may be operational without a brake disk. The word “provided” is understood in particular to mean specially designed, equipped, and/or situated.

With the actuator having an electromagnetic design, a particularly advantageous camshaft adjusting device may be realized which has a short magnetic circuit, as the result of which the camshaft adjusting device has low energy consumption and a rapid response to magnetic energization. In addition, dead time of the camshaft adjusting device may be reduced by a functional separation of the electromagnetic actuator and the brake disk, so that the adjustment times may be shortened. In addition, as a result of the functional separation, a ferromagnetic design of the brake disk may be dispensed with, thus allowing the brake disk to be optimized with regard to weight, size, and/or the like. An “electromagnetic actuator” is understood in particular to mean an actuator which has at least one electromagnet that is provided for displacing the actuating element.

In particular, it is advantageous for the brake disk to have a density of less than 5 g/cm³, so that an advantageous brake disk having low mass inertia may be provided.

Furthermore, it is advantageous for the brake disk to be paramagnetic. A particularly advantageous brake disk may thus be provided.

In addition, it is proposed that the camshaft adjusting device includes a summation gear which has a sun wheel, for example, to which the brake disk is fixedly connected for forming the adjusting input. A phase position between a crankshaft and a camshaft may thus be set in a particularly advantageous manner. A “summation gear” is understood in particular to mean a gear that has at least one planet wheel which is connected to a planet carrier and which in the radial direction is outwardly in meshed connection with an internal gear, and in the radial direction is inwardly in meshed connection with the sun wheel. The planet carrier is preferably connected to the crankshaft in a torque-transmitting manner, and the internal gear is preferably connected to the camshaft in a torque-transmitting manner.

The invention will become more readily apparent from the following description of an exemplary embodiment of the invention with reference to the accompanying drawings. The drawings, the description, and the claims contain numerous features in combination. Those skilled in the art will also advantageously consider the features individually and combine them into further meaningful combinations.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a perspective view of a camshaft adjusting device; and

FIG. 2 shows the camshaft adjusting device in a sectional illustration.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

FIGS. 1 and 2 show a camshaft adjusting device of a motor vehicle internal combustion engine which is provided for adjusting a phase position between a crankshaft of the motor vehicle internal combustion engine, not illustrated here in greater detail, and a camshaft 18 of the motor vehicle internal combustion engine.

For changing the phase position, the camshaft adjusting device has a mechanical braking unit 10 which is provided for supplying a braking torque in order to adjust the phase position. The braking unit 10 has a stationary actuator 11, and a brake disk 14 which rotates during operation of the motor vehicle internal combustion engine. The actuator 11 provides for engagement of the brake disk 14 for generating a braking torque and thus for adjusting the phase position. The actuator 11 and the brake disk 14 are functionally separate from one another, and are each designed as independent components. The actuator 11 and the brake disk 14 are each independently optimized for their specific range of tasks.

The actuator 11 has an electromagnetic design. The actuator has a stationary housing 19, an actuating element 20 which is movable relative to the housing 19, and a stationary electromagnet 21. The housing 19 has a multi-part design. The housing 19 is mounted in a twist- and displacement-free manner. The housing is fixedly connected to a housing, not illustrated here in greater detail, of the motor vehicle internal combustion engine. The housing 19 is fixedly connected to a cylinder head of the motor vehicle internal combustion engine. The electromagnet 21 is fixedly connected to the housing 19 of the actuator 11, and is provided for displacing the actuating element 20. The actuating element 20 is mounted in an axially displaceable and twist-free manner. The actuating element is mounted so as to be displaceable parallel to a rotational axis of the camshaft 18. The actuating element 20 and the brake disk 14 are functionally separate from one another, and have different designs. Upon energization, the electromagnet 21 presses the actuating element 20 against the brake disk 14 and presses the brake disk 14 against the housing 19, thus generating the braking torque. In the absence of energization and thus in a de-energized state of the electromagnet 21, the actuating element 20 and the brake disk 14, as well as the housing 19 and the brake disk 14, in each case are separated by an air gap.

The actuator 11 has a first braking surface 12 and a second braking surface 13 which are situated axially opposite one another and separated at a distance from one another. The first braking surface 12 is mounted in a twist- and displacement-free manner, and the second braking surface 13 is mounted only in a twist-free manner. The second braking surface 13 is axially displaceable relative to the first braking surface 12. The second braking surface 13 is axially displaceable relative to the housing 19. The first braking surface 12 is formed by the stationary housing 19 of the actuator 11, and the second braking surface 13 is formed by the actuating element 20. The actuating element 20 has a brake lining 22 for forming the second braking surface 13. The brake lining 22 of the actuating element 20 forms the second braking surface 13. The brake lining 22 is fixedly 22 connected to the actuating element 20, and is adhesively bonded to the actuating element 20. For generating the braking torque, the second braking surface 13 presses the brake disk 14 axially against the first braking surface 12 due to energization of the electromagnet 21, as the result of which the braking surfaces 12, 13 are each connected to the brake disk 14 via frictional engagement, and the brake disk 14 is decelerated. In the de-energized state of the electromagnet 21, the first braking surface 12 and the second braking surface 13 are each separated from the brake disk 14 by an air gap. In principle, the actuating element 20 and the brake lining 22 may also be formed together as one piece. Of course, it is also conceivable for the first braking surface 12 to likewise be formed by a brake lining which is fixedly connected to the housing 19.

The brake disk 14 is partially situated between the braking surfaces 12, 13. The outer periphery of the brake disk is partially situated between the braking surfaces 12, 13. A portion of the brake disk 14 is situated axially between the braking surfaces 12, 13. The brake disk 14 is designed as a rotating element, and rotates when the motor vehicle internal combustion engine is in operation. The brake disk 14 has a rotational axis that corresponds to the rotational axis of the camshaft 18. The brake disk is situated on a shaft 23 in a twist-free manner.

The brake disk 14 has a density less than 5 g/cm³, and has a paramagnetic design. The brake disk is made of light alloy, and does not have ferromagnetic properties. The brake disk 14 is made of aluminum. The brake disk 14 also may have a brake lining, not illustrated in greater detail here, which is fixedly connected to the brake disk 14. The brake lining is adhesively bonded to the brake disk 14. The brake lining is situated on both axial sides of the brake disk 14, and in each case is provided for contacting the corresponding braking surface 12, 13 of the actuator 11. The brake lining is made of carbon fiber-reinforced plastic (CFRP). In principle, the brake disk 14 and the brake lining may also be formed together as one piece, as the result of which the brake disk 14 is made of carbon fiber-reinforced plastic.

The camshaft adjusting device has a summation gear 16 for a torque-transmitting connection of the crankshaft to the camshaft 18. The summation gear 16 is designed as a three-shaft minus summation gear. The summation gear is designed as a single-stage planet wheel gear. The summation gear 16 has a sun wheel 17 which is fixedly connected to the shaft 23, and thus fixedly connected to the brake disk 14. The shaft 23 and the sun wheel 17 are formed together as one piece. The sun wheel 17 is designed as an adjusting input 15 of the summation gear 16. The brake disk 14 is thus fixedly connected to the adjusting input 15 of the summation gear 16. For adjusting the phase position, the brake disk 14 is fixedly connected to the adjusting input 15.

The summation gear 16 also has a planet carrier 25 which is fixedly connected to a crankshaft sprocket 24 of the camshaft adjusting device. The crankshaft sprocket 24 and the planet carrier 25 are formed together as one piece. The planet carrier 25 is connected to the crankshaft in a torque-transmitting manner by means of the crankshaft sprocket 24, and is driven by the crankshaft. The crankshaft sprocket 24 is designed as a chain wheel, and is connected to the crankshaft in a torque-transmitting manner by means of a chain. The planet carrier 25 guides planet wheels, which mesh with the sun wheel 17, around the rotational axis of the camshaft 18. The planet carrier 25 is designed as an input of the summation gear 16.

The summation gear 16 also has an internal gear 26. The internal gear 26 is fixedly connected to the camshaft 18. The camshaft 18 and the internal gear 26 are formed together as one piece. The internal gear 26 drives the camshaft 18, and meshes with the planet wheels of the summation gear 16. The internal gear 26 is designed as an output of the summation gear 16.

List of Reference Numerals

-   10 Braking unit -   11 Actuator -   12 Braking surface -   13 Braking surface -   14 Brake disk -   15 Adjusting input -   16 Summation gear -   17 Sun wheel -   18 Camshaft -   19 Housing -   20 Actuating element -   21 Electromagnet -   22 Brake lining -   23 Shaft -   24 Crankshaft sprocket -   25 Planet carrier -   26 Internal gear 

What is claimed is:
 1. A camshaft adjusting device of a motor vehicle internal combustion engine having at least one electromagnetically actuated braking unit (10) that includes at least one stationary actuator (11) having at least a first braking surface (12) and a second braking surface (13) which is movable relative to the first braking surface (12), and a brake disk (14) which is functionally separate from the actuator (11) and at least partially situated between the first and second braking surfaces (12, 13) of the actuator (11) and connected to an adjusting input (15) of the camshaft adjusting device.
 2. shaft adjusting device according to claim 1, wherein the brake disk (14) has a density less than 5 g/cm³.
 3. The camshaft adjusting device according to claim 1, wherein the brake disk (14) is of a paramagnetic design.
 4. The camshaft adjusting device according to claim 1, including a summation gear (16) having a sun wheel (17) to which the brake disk (14) is fixedly connected for forming the adjusting input (15). 